Concrete form



April 21, 1925. I w 1,534,215 c. B. HOPKINS CONCRETE FORM Filed July 25 1923 /%6- g z Ceqf/ 5. Hopkins Patented Apr. 21, 1925.

, UNITED STATES :CECIL B. HOPKINS, OF SAN FRANCISCO, CALIFORNIA.

CONCRETE FORM.

Application filed July 23, 1923. Serial No. 653,118.

To wliom it may concern:

Be it known that I, CECIL B. HoPKINs, a

citizen of the United States, and a resident of the cit and county. of San Francisco, State of alifornia, have invented new and useful Concrete Forms, of which the following is a specification.

My invention relates to forms for concrete arches and particularly for concrete joist floors.

An object of the invention is to provide a collapsible end closure for a metallic concrete form.

Another object of the invention is to provide a metallic concrete form which may be readily stripped fromthe concrete, after the concrete has set- Great economy of material and labor in floor construction is found in reinforced concrete floors having'joists at close intervals formed integrally with, the intervening slab and spanning from girder to girder. This construction is particularly valuable in long spans and in such structures as schools, hotels, warehouses and other buildings having moving or vibrating loads. In the practice of m invention I employan arch form, preferab y ofsheet steel in standard size units which conveniently may be 20 inches wide, 15 inchesdeep and inches long. As many units as required by the length of the span are lapped together in desired position upon the horizontal abutment supports which rest upon the false work. The abutment supports may be placed at anydesired height andthe arch forms are vertically adjustable on the supports, so that both the depth of the joist and the thickness of the intervening slab are readily varied to meet the requirements of each job. These metallic arch forms are held in-place by being temporarily secured to the abutment supports, so that after the concrete has been poured and set, the forms may readily be stripped from'the concrete. so that they may be "re-used. In stripping the forms it is necessary to collapse them transversely and this may readily be accomplished at points between the ends of the form. At the ends however, an end closure head must be employed to support the concrete of thewall or girder and it is an object of this invention to make the end closure head in such manner that the. form may be readily collapsed at its end, for the purpose of stripping it from the said concrete,

but it is to be understood that I do not limit myself to such form, since the invention, as set forth in the claims, may be embodied in a plurality of forms.

Referring to said drawings Figure 1 is a vertical sectional View of a portion of concrete joist floor. The section is taken transversely of the joist and shows the arch forms in position.

Figure 2 is a vertical sectional view of {a portion of a floor and of a wall, showing the arch form with the nd closure, in place.

Figure 3 is an end view of the end closure, taken from the outside of the form.

Figure 4 is a detail of a portion of the end closure head on a larger scale showing the means for clipping the two plates of the end closure together.

Figure 5 is a section through the end closure head showing the means for clipping juncture with the top plate so that the thickness'of the joist?) is increased adjacent the floor slab 4 and the floor slab 'is slightly thicker adjacent the joist than on the center between the joists. Posts 5 support the transversely placed beams 6 upon which blocks 7 rest. The abutment supports 8 are.

,arranged upon this false work at the required height to give the desired depth of joist and are spaced apart the requii'ed distance. After the false work has been erected and the abutment supports placed, the arch forms 2 are placed in position and snugly retained against the lateral faces of the abutment supports 8 by nails 9 which are driven through apertures in the form, into the abutment support. These nails 9 are preferably double-headed, so they may readily removed when it is desired to strip the forms from the set concrete. As shown in Figure 2, the edges of each form are provided with a series of apertures 16 through which the nails are driven and these are spaced apart to permit the vertical adjust ment of the form for varying depth of joist, The form units are overlapped at their ends so that a form of any desired length may readily be produced and the holding nails are preferably driven through the overlap. V

The end form unit is provided with an end closure head 12 which supports the concrete of the wall on girder 13 disposed at the end of the form. This end closure head is preferably of the same depth as the form and is of a shape corresponding to the cross sectional contour of the form. The end closure head is made collapsible so that the form may be collapsed for its entire length when it is desired to strip the form from the set concrete. The end closure head comprises, in the present instance, two overlapping plates 14 and 15, which are readily movable relatively to permit the side walls of the form to be moved toward each other. The overlapping edges of the two plates are preferably substantially coincident at the top edge of the head so that their point of meeting serves as a center, as it were, about which the two plates are movable relatively. The amount of overlap preferably increases toward the bottom of the head so that the two plates ma be moved considerable distance respectively without moving the plates from overlapping relation. The plates are preferably provided along the top and side edges with flanges 17 whereby they are secured by rivets or other means, to the end of the form 2.

Means are provided for holding the two overlapping plates 14 and 15 in contact at their overlapping portion to prevent the entry of concrete into the overlapping joint. The inner or overlapped plate 15 is provided adjacent its lower edge with an arcuate slot 18 concentric with the point of coincidence 19 of the two edges. The overlapping or outer plate 14 is provided with an integral tongue 21 which extends through the slot and is bent upward on the inside of the plate15 to form a clip to hold the two plates in contact at the overlapping portion. The clip, however, does not prevent relative movement of the two plates so that the end closure head may be readily collapsed. The form, with the end closure head in place, comprises a continuous crown-sheet, preferably formed in one piece,

and a two piece end closure head adapted to be collapsed .by the bending of the flexible crown sheet, so that the size of the head is reduced when the skirts are moved toward each other for the purpose of collapsing the form to strip it from the concrete.

v I claim: 1

1. A metallic arch form havin a flexible top plate of fixed width and a twopart end closure head in which the two parts are relatively movable on flexure of ghe top plate to permit collapsing of the orm.

2. A metallic arch form having an end 4 4. In a metallic arch form, an end closure head comprising two overlapping p ates, the overlapping edges of the two plates being substantially coincident at the top edge of the head.

5. In a metallic arch form, a flexible top plate of fixed width, and an end closure head comprising two overlapping plates adapted to be moved relatively to collapse the form and means attaching the plates together at their overlapping portions.

6. A form for concrete comprising a metallic arch form having a top plate of fixed width and depending skirts, a colla sible head secured to the form and comprlsing overlapping plates adapted to move with the skirt to collapse the form and means holding the plates together at their overlapping portions while permitting relative movement of the plates.

'7. A form for concrete comprising a metallic arch form having a top plate of fixed width and depending skirts and a collapsible end head secured to the top plate and skirts, movement of the skirts toward each other serving to collapse the head.

8. A metallic arch form comprising a one-piece top plate and a two-part end closure head, the parts being relatively movable to reduce the size of the head when the form is collapsed.

In testimony whereof, I have hereunto set my hand. 7

- CECIL B. HOPKINS. 

